Orange Peel Topography as Affected by a Preharvest Plastic Spray1

Abstract

Abstract Mature ‘Valencia’ oranges when sprayed 2 months prior to harvest in the spring of 1969 with a 1 or 3% solution of Pinolene, a liquid polyterpene plastic film former, were greener at harvest, lost less wt, and had better appearance than control fruit after 9 weeks of storage. Fresh and fixed sections of peel from control and plastic-treated ‘Hamlin’ orange fruit from trees sprayed 2 months before harvest with a 1% solution of Pinolene were observed with a scanning-electron microscope after harvest. The surfaces of control fruit showed considerable variation with some areas having essentially no epicuticular wax platelets while other areas were completely covered. On sprayed fruit, plastic often partially masked the wax platelet edges. On control fruit, the openings to the outer stomatal chambers were usually unobstructed although the stomatal pores between the guard cells were often plugged. In most cases, the openings to the outer stomatal chambers of sprayed fruit were partially or completely obstructed with plastic.